Auckland city beaches do not yet have signs warning people not to swim or take children to the beach, despite a serious health alert issued on Tuesday.
The alert is for beaches on the east coast and Hauraki Gulf after at least two dogs died and several more became ill from unexplained causes.
Other sealife, including penguins and fish, have been found dead on beaches.
The Auckland Regional Public Health Service has phoned affected councils on Wednesday, saying they must have the signs up urgently.
Auckland City Council says it has not had time to print the signs and will put them up on Thursday.
However, it says it has officers monitoring the beaches from Panmure to Pt Chevalier.
North Shore City Council environment protection officer Duffy Visser says they have had signs warning of danger to dogs up for a few days.
Manukau City Council says it also now has signs in place.
A biosecurity expert at the Ministry of Agriculture and Forestry says toxic blue green algae is the most likely cause of the dogs' deaths and illnesses. However, more tests are needed.
However, Naya Brangenberg says it appears unlikely that the dog illness is linked to dead fish and birds found along the coast.